Coordinates in ggplot2 in R

Most popular graphs such as line and bar charts are drawn using Cartesian coordinates.

coord_cartesian

When we plot a chart, Cartesian Coordinates is the default coordinate system. For example, the following chart plots Duration of Credit on x-axis and Credit Amount on y-axis. The points are colors by the factor Loan.Quality.

1g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Credit.amount,color=Loan.Quality))
2g+geom_point()+geom_smooth()+coord_cartesian()
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coord_flip

By specifying coord_flip, it will still use the cartesian system, but flip the two axis.

1g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Credit.amount,color=Loan.Quality))
2g+geom_point()+geom_smooth()+coord_flip()
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Zooming In

We can use the coordinates layer to zoom in to a plot by setting limits. The various options are below:

1coord_cartesian(xlim = NULL, ylim = NULL, expand = TRUE)
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• xlim, ylim: Limits for the x and y axes.
• expand: If TRUE, the default, adds a small expansion factor to the limits to ensure that data and axes don't overlap. If FALSE, limits are taken exactly from the data or xlim/ylim

Let's say we want to zoom in our plot to show the points where the Duration of credit is between 40 and 60. This can be done as follows:

1g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Credit.amount,color=Loan.Quality))
2g+geom_point()+geom_smooth()+coord_cartesian(c(40,60))
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Aspect Ratio

We can set the aspect ratio of a plot with coord_fixed() or coord_equal(). Both use aspect = 1 (1:1) as a default. For example, consider the following plot which plots Duration of Credit on x-axis and Age on y-axis.

1g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Age.in.years,color=Loan.Quality))
2g+geom_point()+geom_smooth()
3

We can add the coordinate coord_equal() to make the aspect ratio 1:1.

1g <- ggplot(df,aes(x=Duration.of.Credit..in.months.,y=Age.in.years,color=Loan.Quality))
2g+geom_point()+geom_smooth()+coord_equal()
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